// Copyright 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Known Issues:
//
// * Patterns are not implemented.
// * Radial gradient are not implemented. The VML version of these look very
//   different from the canvas one.
// * Clipping paths are not implemented.
// * Coordsize. The width and height attribute have higher priority than the
//   width and height style values which isn't correct.
// * Painting mode isn't implemented.
// * Canvas width/height should is using content-box by default. IE in
//   Quirks mode will draw the canvas using border-box. Either change your
//   doctype to HTML5
//   (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
//   or use Box Sizing Behavior from WebFX
//   (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
// * Optimize. There is always room for speed improvements.

// only add this code if we do not already have a canvas implementation
if (!window.CanvasRenderingContext2D) {

	(function() {

		// alias some functions to make (compiled) code shorter
		var m = Math;
		var mr = m.round;
		var ms = m.sin;
		var mc = m.cos;

		// this is used for sub pixel precision
		var Z = 10;
		var Z2 = Z / 2;

		var G_vmlCanvasManager_ = {
			init : function(opt_doc) {
				var doc = opt_doc || document;
				if (/MSIE/.test(navigator.userAgent) && !window.opera) {
					var self = this;
					doc.attachEvent("onreadystatechange", function() {
						self.init_(doc);
					});
				}
			},

			init_ : function(doc) {
				if (doc.readyState == "complete") {
					// create xmlns
					if (!doc.namespaces["g_vml_"]) {
						doc.namespaces.add("g_vml_",
								"urn:schemas-microsoft-com:vml");
					}

					// setup default css
					var ss = doc.createStyleSheet();
					ss.cssText = "canvas{display:inline-block;overflow:hidden;"
							+
							// default size is 300x150 in Gecko and Opera
							"text-align:left;width:300px;height:150px}"
							+ "g_vml_\\:*{behavior:url(#default#VML)}";

					// find all canvas elements
					var els = doc.getElementsByTagName("canvas");
					for (var i = 0; i < els.length; i++) {
						if (!els[i].getContext) {
							this.initElement(els[i]);
						}
					}
				}
			},

			fixElement_ : function(el) {
				// in IE before version 5.5 we would need to add HTML: to the
				// tag name
				// but we do not care about IE before version 6
				var outerHTML = el.outerHTML;

				var newEl = el.ownerDocument.createElement(outerHTML);
				// if the tag is still open IE has created the children as
				// siblings and
				// it has also created a tag with the name "/FOO"
				if (outerHTML.slice(-2) != "/>") {
					var tagName = "/" + el.tagName;
					var ns;
					// remove content
					while ((ns = el.nextSibling) && ns.tagName != tagName) {
						ns.removeNode();
					}
					// remove the incorrect closing tag
					if (ns) {
						ns.removeNode();
					}
				}
				el.parentNode.replaceChild(newEl, el);
				return newEl;
			},

			/**
			 * Public initializes a canvas element so that it can be used as
			 * canvas element from now on. This is called automatically before
			 * the page is loaded but if you are creating elements using
			 * createElement you need to make sure this is called on the
			 * element.
			 * 
			 * @param {HTMLElement}
			 *            el The canvas element to initialize.
			 * @return {HTMLElement} the element that was created.
			 */
			initElement : function(el) {
				el = this.fixElement_(el);
				el.getContext = function() {
					if (this.context_) {
						return this.context_;
					}
					return this.context_ = new CanvasRenderingContext2D_(this);
				};

				// do not use inline function because that will leak memory
				el.attachEvent('onpropertychange', onPropertyChange);
				el.attachEvent('onresize', onResize);

				var attrs = el.attributes;
				if (attrs.width && attrs.width.specified) {
					// TODO: use runtimeStyle and coordsize
					// el.getContext().setWidth_(attrs.width.nodeValue);
					el.style.width = attrs.width.nodeValue + "px";
				} else {
					el.width = el.clientWidth;
				}
				if (attrs.height && attrs.height.specified) {
					// TODO: use runtimeStyle and coordsize
					// el.getContext().setHeight_(attrs.height.nodeValue);
					el.style.height = attrs.height.nodeValue + "px";
				} else {
					el.height = el.clientHeight;
				}
				// el.getContext().setCoordsize_()
				return el;
			}
		};

		function onPropertyChange(e) {
			var el = e.srcElement;

			switch (e.propertyName) {
			case 'width':
				el.style.width = el.attributes.width.nodeValue + "px";
				el.getContext().clearRect();
				break;
			case 'height':
				el.style.height = el.attributes.height.nodeValue + "px";
				el.getContext().clearRect();
				break;
			}
		}

		function onResize(e) {
			var el = e.srcElement;
			if (el.firstChild) {
				el.firstChild.style.width = el.clientWidth + 'px';
				el.firstChild.style.height = el.clientHeight + 'px';
			}
		}

		G_vmlCanvasManager_.init();

		// precompute "00" to "FF"
		var dec2hex = [];
		for (var i = 0; i < 16; i++) {
			for (var j = 0; j < 16; j++) {
				dec2hex[i * 16 + j] = i.toString(16) + j.toString(16);
			}
		}

		function createMatrixIdentity() {
			return [ [ 1, 0, 0 ], [ 0, 1, 0 ], [ 0, 0, 1 ] ];
		}

		function matrixMultiply(m1, m2) {
			var result = createMatrixIdentity();

			for (var x = 0; x < 3; x++) {
				for (var y = 0; y < 3; y++) {
					var sum = 0;

					for (var z = 0; z < 3; z++) {
						sum += m1[x][z] * m2[z][y];
					}

					result[x][y] = sum;
				}
			}
			return result;
		}

		function copyState(o1, o2) {
			o2.fillStyle = o1.fillStyle;
			o2.lineCap = o1.lineCap;
			o2.lineJoin = o1.lineJoin;
			o2.lineWidth = o1.lineWidth;
			o2.miterLimit = o1.miterLimit;
			o2.shadowBlur = o1.shadowBlur;
			o2.shadowColor = o1.shadowColor;
			o2.shadowOffsetX = o1.shadowOffsetX;
			o2.shadowOffsetY = o1.shadowOffsetY;
			o2.strokeStyle = o1.strokeStyle;
			o2.arcScaleX_ = o1.arcScaleX_;
			o2.arcScaleY_ = o1.arcScaleY_;
		}

		function processStyle(styleString) {
			var str, alpha = 1;

			styleString = String(styleString);
			if (styleString.substring(0, 3) == "rgb") {
				var start = styleString.indexOf("(", 3);
				var end = styleString.indexOf(")", start + 1);
				var guts = styleString.substring(start + 1, end).split(",");

				str = "#";
				for (var i = 0; i < 3; i++) {
					str += dec2hex[Number(guts[i])];
				}

				if ((guts.length == 4) && (styleString.substr(3, 1) == "a")) {
					alpha = guts[3];
				}
			} else {
				str = styleString;
			}

			return [ str, alpha ];
		}

		function processLineCap(lineCap) {
			switch (lineCap) {
			case "butt":
				return "flat";
			case "round":
				return "round";
			case "square":
			default:
				return "square";
			}
		}

		/**
		 * This class implements CanvasRenderingContext2D interface as described
		 * by the WHATWG.
		 * 
		 * @param {HTMLElement}
		 *            surfaceElement The element that the 2D context should be
		 *            associated with
		 */
		function CanvasRenderingContext2D_(surfaceElement) {
			this.m_ = createMatrixIdentity();

			this.mStack_ = [];
			this.aStack_ = [];
			this.currentPath_ = [];

			// Canvas context properties
			this.strokeStyle = "#000";
			this.fillStyle = "#000";

			this.lineWidth = 1;
			this.lineJoin = "miter";
			this.lineCap = "butt";
			this.miterLimit = Z * 1;
			this.globalAlpha = 1;
			this.canvas = surfaceElement;

			var el = surfaceElement.ownerDocument.createElement('div');
			el.style.width = surfaceElement.clientWidth + 'px';
			el.style.height = surfaceElement.clientHeight + 'px';
			el.style.overflow = 'hidden';
			el.style.position = 'absolute';
			surfaceElement.appendChild(el);

			this.element_ = el;
			this.arcScaleX_ = 1;
			this.arcScaleY_ = 1;
		}
		;

		var contextPrototype = CanvasRenderingContext2D_.prototype;
		contextPrototype.clearRect = function() {
			this.element_.innerHTML = "";
			this.currentPath_ = [];
		};

		contextPrototype.beginPath = function() {
			// TODO: Branch current matrix so that save/restore has no effect
			// as per safari docs.

			this.currentPath_ = [];
		};

		contextPrototype.moveTo = function(aX, aY) {
			this.currentPath_.push({
				type : "moveTo",
				x : aX,
				y : aY
			});
			this.currentX_ = aX;
			this.currentY_ = aY;
		};

		contextPrototype.lineTo = function(aX, aY) {
			this.currentPath_.push({
				type : "lineTo",
				x : aX,
				y : aY
			});
			this.currentX_ = aX;
			this.currentY_ = aY;
		};

		contextPrototype.bezierCurveTo = function(aCP1x, aCP1y, aCP2x, aCP2y,
				aX, aY) {
			this.currentPath_.push({
				type : "bezierCurveTo",
				cp1x : aCP1x,
				cp1y : aCP1y,
				cp2x : aCP2x,
				cp2y : aCP2y,
				x : aX,
				y : aY
			});
			this.currentX_ = aX;
			this.currentY_ = aY;
		};

		contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {
			// the following is lifted almost directly from
			// http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes
			var cp1x = this.currentX_ + 2.0 / 3.0 * (aCPx - this.currentX_);
			var cp1y = this.currentY_ + 2.0 / 3.0 * (aCPy - this.currentY_);
			var cp2x = cp1x + (aX - this.currentX_) / 3.0;
			var cp2y = cp1y + (aY - this.currentY_) / 3.0;
			this.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, aX, aY);
		};

		contextPrototype.arc = function(aX, aY, aRadius, aStartAngle,
				aEndAngle, aClockwise) {
			aRadius *= Z;
			var arcType = aClockwise ? "at" : "wa";

			var xStart = aX + (mc(aStartAngle) * aRadius) - Z2;
			var yStart = aY + (ms(aStartAngle) * aRadius) - Z2;

			var xEnd = aX + (mc(aEndAngle) * aRadius) - Z2;
			var yEnd = aY + (ms(aEndAngle) * aRadius) - Z2;

			// IE won't render arches drawn counter clockwise if xStart == xEnd.
			if (xStart == xEnd && !aClockwise) {
				xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use
									// something
				// that can be represented in binary
			}

			this.currentPath_.push({
				type : arcType,
				x : aX,
				y : aY,
				radius : aRadius,
				xStart : xStart,
				yStart : yStart,
				xEnd : xEnd,
				yEnd : yEnd
			});

		};

		contextPrototype.rect = function(aX, aY, aWidth, aHeight) {
			this.moveTo(aX, aY);
			this.lineTo(aX + aWidth, aY);
			this.lineTo(aX + aWidth, aY + aHeight);
			this.lineTo(aX, aY + aHeight);
			this.closePath();
		};

		contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {
			// Will destroy any existing path (same as FF behaviour)
			this.beginPath();
			this.moveTo(aX, aY);
			this.lineTo(aX + aWidth, aY);
			this.lineTo(aX + aWidth, aY + aHeight);
			this.lineTo(aX, aY + aHeight);
			this.closePath();
			this.stroke();
		};

		contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {
			// Will destroy any existing path (same as FF behaviour)
			this.beginPath();
			this.moveTo(aX, aY);
			this.lineTo(aX + aWidth, aY);
			this.lineTo(aX + aWidth, aY + aHeight);
			this.lineTo(aX, aY + aHeight);
			this.closePath();
			this.fill();
		};

		contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {
			var gradient = new CanvasGradient_("gradient");
			return gradient;
		};

		contextPrototype.createRadialGradient = function(aX0, aY0, aR0, aX1,
				aY1, aR1) {
			var gradient = new CanvasGradient_("gradientradial");
			gradient.radius1_ = aR0;
			gradient.radius2_ = aR1;
			gradient.focus_.x = aX0;
			gradient.focus_.y = aY0;
			return gradient;
		};

		contextPrototype.drawImage = function(image, var_args) {
			var dx, dy, dw, dh, sx, sy, sw, sh;

			// to find the original width we overide the width and height
			var oldRuntimeWidth = image.runtimeStyle.width;
			var oldRuntimeHeight = image.runtimeStyle.height;
			image.runtimeStyle.width = 'auto';
			image.runtimeStyle.height = 'auto';

			// get the original size
			var w = image.width;
			var h = image.height;

			// and remove overides
			image.runtimeStyle.width = oldRuntimeWidth;
			image.runtimeStyle.height = oldRuntimeHeight;

			if (arguments.length == 3) {
				dx = arguments[1];
				dy = arguments[2];
				sx = sy = 0;
				sw = dw = w;
				sh = dh = h;
			} else if (arguments.length == 5) {
				dx = arguments[1];
				dy = arguments[2];
				dw = arguments[3];
				dh = arguments[4];
				sx = sy = 0;
				sw = w;
				sh = h;
			} else if (arguments.length == 9) {
				sx = arguments[1];
				sy = arguments[2];
				sw = arguments[3];
				sh = arguments[4];
				dx = arguments[5];
				dy = arguments[6];
				dw = arguments[7];
				dh = arguments[8];
			} else {
				throw "Invalid number of arguments";
			}

			var d = this.getCoords_(dx, dy);

			var w2 = sw / 2;
			var h2 = sh / 2;

			var vmlStr = [];

			var W = 10;
			var H = 10;

			// For some reason that I've now forgotten, using divs didn't work
			vmlStr.push(' <g_vml_:group', ' coordsize="', Z * W, ',', Z * H,
					'"', ' coordorigin="0,0"', ' style="width:', W, ';height:',
					H, ';position:absolute;');

			// If filters are necessary (rotation exists), create them
			// filters are bog-slow, so only create them if abbsolutely
			// necessary
			// The following check doesn't account for skews (which don't exist
			// in the canvas spec (yet) anyway.

			if (this.m_[0][0] != 1 || this.m_[0][1]) {
				var filter = [];

				// Note the 12/21 reversal
				filter.push("M11='", this.m_[0][0], "',", "M12='",
						this.m_[1][0], "',", "M21='", this.m_[0][1], "',",
						"M22='", this.m_[1][1], "',", "Dx='", mr(d.x / Z),
						"',", "Dy='", mr(d.y / Z), "'");

				// Bounding box calculation (need to minimize displayed area so
				// that
				// filters don't waste time on unused pixels.
				var max = d;
				var c2 = this.getCoords_(dx + dw, dy);
				var c3 = this.getCoords_(dx, dy + dh);
				var c4 = this.getCoords_(dx + dw, dy + dh);

				max.x = Math.max(max.x, c2.x, c3.x, c4.x);
				max.y = Math.max(max.y, c2.y, c3.y, c4.y);

				vmlStr
						.push(
								"padding:0 ",
								mr(max.x / Z),
								"px ",
								mr(max.y / Z),
								"px 0;filter:progid:DXImageTransform.Microsoft.Matrix(",
								filter.join(""), ", sizingmethod='clip');")
			} else {
				vmlStr
						.push("top:", mr(d.y / Z), "px;left:", mr(d.x / Z),
								"px;")
			}

			vmlStr.push(' ">', '<g_vml_:image src="', image.src, '"',
					' style="width:', Z * dw, ';', ' height:', Z * dh, ';"',
					' cropleft="', sx / w, '"', ' croptop="', sy / h, '"',
					' cropright="', (w - sx - sw) / w, '"', ' cropbottom="', (h
							- sy - sh)
							/ h, '"', ' />', '</g_vml_:group>');

			this.element_.insertAdjacentHTML("BeforeEnd", vmlStr.join(""));
		};

		contextPrototype.stroke = function(aFill) {
			var lineStr = [];
			var lineOpen = false;
			var a = processStyle(aFill ? this.fillStyle : this.strokeStyle);
			var color = a[0];
			var opacity = a[1] * this.globalAlpha;

			var W = 10;
			var H = 10;

			lineStr.push('<g_vml_:shape', ' fillcolor="', color, '"',
					' filled="', Boolean(aFill), '"',
					' style="position:absolute;width:', W, ';height:', H, ';"',
					' coordorigin="0 0" coordsize="', Z * W, ' ', Z * H, '"',
					' stroked="', !aFill, '"', ' strokeweight="',
					this.lineWidth, '"', ' strokecolor="', color, '"',
					' path="');

			var newSeq = false;
			var min = {
				x : null,
				y : null
			};
			var max = {
				x : null,
				y : null
			};

			for (var i = 0; i < this.currentPath_.length; i++) {
				var p = this.currentPath_[i];

				if (p.type == "moveTo") {
					lineStr.push(" m ");
					var c = this.getCoords_(p.x, p.y);
					lineStr.push(mr(c.x), ",", mr(c.y));
				} else if (p.type == "lineTo") {
					lineStr.push(" l ");
					var c = this.getCoords_(p.x, p.y);
					lineStr.push(mr(c.x), ",", mr(c.y));
				} else if (p.type == "close") {
					lineStr.push(" x ");
				} else if (p.type == "bezierCurveTo") {
					lineStr.push(" c ");
					var c = this.getCoords_(p.x, p.y);
					var c1 = this.getCoords_(p.cp1x, p.cp1y);
					var c2 = this.getCoords_(p.cp2x, p.cp2y);
					lineStr.push(mr(c1.x), ",", mr(c1.y), ",", mr(c2.x), ",",
							mr(c2.y), ",", mr(c.x), ",", mr(c.y));
				} else if (p.type == "at" || p.type == "wa") {
					lineStr.push(" ", p.type, " ");
					var c = this.getCoords_(p.x, p.y);
					var cStart = this.getCoords_(p.xStart, p.yStart);
					var cEnd = this.getCoords_(p.xEnd, p.yEnd);

					lineStr.push(mr(c.x - this.arcScaleX_ * p.radius), ",",
							mr(c.y - this.arcScaleY_ * p.radius), " ", mr(c.x
									+ this.arcScaleX_ * p.radius), ",", mr(c.y
									+ this.arcScaleY_ * p.radius), " ",
							mr(cStart.x), ",", mr(cStart.y), " ", mr(cEnd.x),
							",", mr(cEnd.y));
				}

				// TODO: Following is broken for curves due to
				// move to proper paths.

				// Figure out dimensions so we can do gradient fills
				// properly
				if (c) {
					if (min.x == null || c.x < min.x) {
						min.x = c.x;
					}
					if (max.x == null || c.x > max.x) {
						max.x = c.x;
					}
					if (min.y == null || c.y < min.y) {
						min.y = c.y;
					}
					if (max.y == null || c.y > max.y) {
						max.y = c.y;
					}
				}
			}
			lineStr.push(' ">');

			if (typeof this.fillStyle == "object") {
				var focus = {
					x : "50%",
					y : "50%"
				};
				var width = (max.x - min.x);
				var height = (max.y - min.y);
				var dimension = (width > height) ? width : height;

				focus.x = mr((this.fillStyle.focus_.x / width) * 100 + 50)
						+ "%";
				focus.y = mr((this.fillStyle.focus_.y / height) * 100 + 50)
						+ "%";

				var colors = [];

				// inside radius (%)
				if (this.fillStyle.type_ == "gradientradial") {
					var inside = (this.fillStyle.radius1_ / dimension * 100);

					// percentage that outside radius exceeds inside radius
					var expansion = (this.fillStyle.radius2_ / dimension * 100)
							- inside;
				} else {
					var inside = 0;
					var expansion = 100;
				}

				var insidecolor = {
					offset : null,
					color : null
				};
				var outsidecolor = {
					offset : null,
					color : null
				};

				// We need to sort 'colors' by percentage, from 0 > 100
				// otherwise ie
				// won't interpret it correctly
				this.fillStyle.colors_.sort(function(cs1, cs2) {
					return cs1.offset - cs2.offset;
				});

				for (var i = 0; i < this.fillStyle.colors_.length; i++) {
					var fs = this.fillStyle.colors_[i];

					colors.push((fs.offset * expansion) + inside, "% ",
							fs.color, ",");

					if (fs.offset > insidecolor.offset
							|| insidecolor.offset == null) {
						insidecolor.offset = fs.offset;
						insidecolor.color = fs.color;
					}

					if (fs.offset < outsidecolor.offset
							|| outsidecolor.offset == null) {
						outsidecolor.offset = fs.offset;
						outsidecolor.color = fs.color;
					}
				}
				colors.pop();

				lineStr.push('<g_vml_:fill', ' color="', outsidecolor.color,
						'"', ' color2="', insidecolor.color, '"', ' type="',
						this.fillStyle.type_, '"', ' focusposition="', focus.x,
						', ', focus.y, '"', ' colors="', colors.join(""), '"',
						' opacity="', opacity, '" />');
			} else if (aFill) {
				lineStr.push('<g_vml_:fill color="', color, '" opacity="',
						opacity, '" />');
			} else {
				lineStr.push('<g_vml_:stroke', ' opacity="', opacity, '"',
						' joinstyle="', this.lineJoin, '"', ' miterlimit="',
						this.miterLimit, '"', ' endcap="',
						processLineCap(this.lineCap), '"', ' weight="',
						this.lineWidth, 'px"', ' color="', color, '" />');
			}

			lineStr.push("</g_vml_:shape>");

			this.element_.insertAdjacentHTML("beforeEnd", lineStr.join(""));

			this.currentPath_ = [];
		};

		contextPrototype.fill = function() {
			this.stroke(true);
		}

		contextPrototype.closePath = function() {
			this.currentPath_.push({
				type : "close"
			});
		};

		/**
		 * @private
		 */
		contextPrototype.getCoords_ = function(aX, aY) {
			return {
				x : Z
						* (aX * this.m_[0][0] + aY * this.m_[1][0] + this.m_[2][0])
						- Z2,
				y : Z
						* (aX * this.m_[0][1] + aY * this.m_[1][1] + this.m_[2][1])
						- Z2
			}
		};

		contextPrototype.save = function() {
			var o = {};
			copyState(this, o);
			this.aStack_.push(o);
			this.mStack_.push(this.m_);
			this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
		};

		contextPrototype.restore = function() {
			copyState(this.aStack_.pop(), this);
			this.m_ = this.mStack_.pop();
		};

		contextPrototype.translate = function(aX, aY) {
			var m1 = [ [ 1, 0, 0 ], [ 0, 1, 0 ], [ aX, aY, 1 ] ];

			this.m_ = matrixMultiply(m1, this.m_);
		};

		contextPrototype.rotate = function(aRot) {
			var c = mc(aRot);
			var s = ms(aRot);

			var m1 = [ [ c, s, 0 ], [ -s, c, 0 ], [ 0, 0, 1 ] ];

			this.m_ = matrixMultiply(m1, this.m_);
		};

		contextPrototype.scale = function(aX, aY) {
			this.arcScaleX_ *= aX;
			this.arcScaleY_ *= aY;
			var m1 = [ [ aX, 0, 0 ], [ 0, aY, 0 ], [ 0, 0, 1 ] ];

			this.m_ = matrixMultiply(m1, this.m_);
		};

		/** ****** STUBS ******* */
		contextPrototype.clip = function() {
			// TODO: Implement
		};

		contextPrototype.arcTo = function() {
			// TODO: Implement
		};

		contextPrototype.createPattern = function() {
			return new CanvasPattern_;
		};

		// Gradient / Pattern Stubs
		function CanvasGradient_(aType) {
			this.type_ = aType;
			this.radius1_ = 0;
			this.radius2_ = 0;
			this.colors_ = [];
			this.focus_ = {
				x : 0,
				y : 0
			};
		}

		CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
			aColor = processStyle(aColor);
			this.colors_.push({
				offset : 1 - aOffset,
				color : aColor
			});
		};

		function CanvasPattern_() {
		}

		// set up externs
		G_vmlCanvasManager = G_vmlCanvasManager_;
		CanvasRenderingContext2D = CanvasRenderingContext2D_;
		CanvasGradient = CanvasGradient_;
		CanvasPattern = CanvasPattern_;

	})();

} // if
